Substrate conveyer robot

ABSTRACT

The invention provides a substrate conveyer robot that enables the conveyance, handover and takeout of a substrate, to and from a container disposed in an arbitrary position and direction within the accessible range of the robot hand. The substrate conveyer robot is provided with the rotation base driven to rotate by a first motor inside the body of the robot, which has a pivotal center. A first spindle is protruded in a state indifferent to a rotation of the rotation base, which is positioned coaxially with the pivotal center on an upper part of the rotation base, and is driven to rotate by a second motor, and one end of a first arm is attached to the first spindle. A second spindle is protruded on the other end of the first arm in a state indifferent to the rotation of the first arm, which is rotated by a gear rate 2:1, accompanied with the rotation of the first arm, and one end of a second arm is attached to the second spindle. A third spindle is protruded on the other end of the second arm in a state indifferent to the rotation of the second arm, which is rotated by a gear rate 1:2, accompanied with the rotation of the second arm, and a distance between the first spindle and the second spindle is equal to a distance between the second spindle and the third spindle. One end of a third arm is attached to the third spindle, and a hand for holding a substrate is firmly attached on the other end of the third arm. Also, a control device is provided which controls the rotation angle θ of the rotation base and the rotation angle φ of the first arm in such a manner that the center point of the substrate held by the hand, deviating from the pivotal center by a constant distance h, moves linearly to the body of the robot on the straight line in an arbitrary direction within an accessible range of the hand, and the substrate is handed over and taken out to and from the container, while the substrate is being rotated

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a robot for conveying asubstrate, for example, a substrate conveyer robot suitable for use inconveying a semiconductor wafer substrate to hand over to a containersuch as a cassette, and taking it out from the container.

[0003] 2. Related Art

[0004] Conventionally, there has been a generally used wafer substrateconveyer robot of the belt link type that possesses an armexpansion/contraction mechanism with three arms of a first through athird arm, in which the gear rate of the pulley furnished on therotation spindle of each arm is 2:1:2. This type of robot conveys thesubstrate horizontally by the control of only two axes. One of them is arobot advancing/retreating axis R for linearly advancing and retreatingthe third arm by the belt link mechanism, and another one is a robotrevolving axis θfor revolving the rotary base of the robot. Further,with a lifting/lowering operation of the whole arms, the robot performsthe handover and takeout of the substrate to and from the cassette.

[0005] In general, a substrate conveyer robot 01 possesses the armexpansion/contraction mechanism composed of three arms 05, 07, 09, andthe two control axes, the robot revolving axis θand the robotadvancing/retreating axis R. As illustrated in FIG. 11, the center ofthe substrate 030 held by a hand 010 fixed on the third arm 09 advancesand retreats along a straight line J0 that passes through the center ofa rotary shaft (=a first, spindle; this is positioned on the same axisas the robot revolving axis θ) of the first arm 05, thereby thesubstrate conveyer robot 01 is designed to convey and hand over thesubstrate 030 only to a cassette 032 that is disposed to face the frontthereof toward the line J0. Here, the straight line J0 coincides withthe robot advancing/retreating axis R.

[0006] The cassette 032 forms in a quadrangle, and permits the substrate030 to be inserted only from one direction vertical to an aperture planethereof; and, in case of the conventional robot with two axes, asillustrated in FIG. 11(a) through FIG. 11(c), the robot 010 or cassette032 has been required to be disposed in such a manner that the centerline of the cassette 032 perpendicular to the aperture plane thereofalways passes through the robot revolving axis θ(the pivotal center).And, first of all, a rotation base 03 is rotated around the robotrevolving axis θ, and the third arm 09 is positioned right in front ofthe cassette 032. Next, the third arm 09 is moved to advance and retreatlinearly along the robot advancing/retreating axis R (the straight lineJ0), thereby handing over and taking out the substrate 030 to and fromthe cassette 032. In other words, the control of the rotating movementaround the robot revolving axis θ and the control of the advancing andretreating movement along the robot advancing/retreating axis R havebeen carried out sequentially, and not simultaneously.

[0007] As described above, most of the conventional robots possessingtwo control axes, the robot revolving axis θ and the robotadvancing/retreating axis R, were not assumed to combine the control ofthe rotating movement around the robot revolving axis θ and the controlof the advancing and retreating movement along the robotadvancing/retreating axis R simultaneously. Therefore, the conventionalrobots could only convey to hand over and take out the substrate to andfrom the cassette that is positioned in a radial manner to (in otherwords, positioned right in front of) the robot revolving axis θ.

[0008] Therefore, in order for the robot to maintain the control toconvey to hand over and take out the substrate to and from the cassette,even in case the cassette is positioned so as to face right to anarbitrary straight line deviating from the robot revolving axis θ, therewas no other way than to use such a robot that is disclosed in JapanesePatent Laid-Open No. Hei 11(1999)-33948 Publication. This robot adds oneaxis to the foregoing two axes (two control axes) to freely control theposition and direction of the hand engaged with the last arm in thehorizontal plane.

[0009] However, the use of the robot disclosed in the above publicationrequired an extra driving source for driving the one axis added, andmade the control complicated at the same time, thus raising the cost.

[0010] The substrate conveyer robot illustrated in FIG. 11 is a singlearm sequence type, possessing one sequence of an armexpansion/contraction mechanism composed of three arms. Also, a doublearm sequence type substrate conveyer robot that possesses two sequences(a pair) of bilaterally symmetrical arm expansion/contraction mechanismshas the same problem as described above.

SUMMARY OF INVENTION

[0011] The present invention has been made in view of solving the aboveproblems that the conventional substrate conveyer robot possesses, andan object of the invention is to provide a substrate conveyer robot thatcan hand over and take out a substrate to and from a container disposedin an arbitrary position and direction within an accessible range of therobot hand, with a number of the control axes as smaller as possible, ata low production cost.

[0012] To accomplish the foregoing object, according to one aspect ofthe invention, the substrate conveyer robot is provided with a rotationbase 3 driven to rotate by a first motor M1 inside the body of therobot, which has a pivotal center Q, in which a first spindle 4 isprotruded in a state indifferent to the rotation of the rotation base 3,which is positioned coaxially with the pivotal center Q on an upper partof the rotation base 3, and is driven to rotate by a second motor M2;one end of a first arm 5 is attached to the first spindle 4; a secondspindle 6 is protruded on the other end of the first arm 5 in a stateindifferent to the rotation of the first arm 5, which is rotated by agear rate 2:1 by way of pulleys and a timing belt inside the first arm5, accompanied with the rotation of the first arm 5; one end of a secondarm 7 is attached to the second spindle 6; a third spindle 8 isprotruded on the other end of the second arm 7 in a state indifferent tothe rotation of the second arm 7, which is rotated by a gear rate 1:2 byway of pulleys and a timing belt inside the second arm 7, accompaniedwith the rotation of the second arm 7; a distance between the firstspindle 4 and the second spindle 6 is equal to a distance between thesecond spindle 6 and the third spindle 8; one end of a third arm 9 isattached to the third spindle 8; a hand 10 for holding a substrate isfirmly attached on the other end of the third arm 9; and, when therotation angle of the rotation base 3 is represented by 0 and therotation angle of the first arm 5 is represented by φ, a control deviceis provided which controls the rotation angles θ and φ in such a mannerthat a center point of the substrate held by the hand 10, deviating fromthe pivotal center Q, moves linearly to the body of the robot on thestraight line H in an arbitrary direction within an accessible range ofthe hand 10, and the substrate is handed over and taken out to and froma container, while the substrate is being rotated.

[0013] The substrate conveyer robot with the above construction is theso-called single arm sequence type substrate conveyer robot having asingle sequence of an arm expansion/contraction mechanism that containsthe first through the third arms 5, 7, and 9. The control devicecontrols the rotation angle θ of the rotation base 3 provided in thebody of the robot and the rotation angle φ of the first arm 5, in such amanner that the center point of the substrate held by the hand 10,deviating from the pivotal center Q, moves linearly to the body of therobot on the straight line H in an arbitrary direction within theaccessible range of the hand 10, and the substrate is handed over andtaken out to and from the container, while the substrate is beingrotated. Therefore, when compared with the conventional single armsequence type substrate conveyer robot, the invention can provide asubstrate conveyer robot that can hand over and take out the substrateto and from the container disposed in an arbitrary position anddirection within the accessible range of the hand 10 of the robot,without increasing the number of the control axes, at a low productioncost.

[0014] Further, in the foregoing construction, the control devicepreferably controls the rotation angles θ and φ each so as to satisfy:

{m+2L sin(φ)}sin(θ)=h(constant),

[0015] where it is assumed that the center point of the substratedeviates from the pivotal center Q by a constant distance h, and moveslinearly to the body of the robot on the straight line H in an arbitrarydirection within the accessible range of the hand 10, and that thedistance between the first spindle 4 and the second spindle 6 and thedistance between the second spindle 6 and the third spindle 8 arerepresented by L, and a distance between the third spindle 8 and thecenter of the substrate is represented by m. As the result, thecombination control of these rotation angles θ and φ becomes verysimple, in which the center point of the substrate held by the hand 10,deviating from the pivotal center Q, moves linearly to the body of therobot on the straight line H in an arbitrary direction within theaccessible range of the hand 10, and the substrate is handed over andtaken out to and from the container, while the substrate is beingrotated.

[0016] According to another aspect of the invention, the substrateconveyer robot is provided with a rotation base 3 driven to rotate by afirst motor M1 inside the body of the robot, which has a pivotal centerQ, in which first spindles 4, 4′ are protruded in a state indifferent toa rotation of the rotation base 3, which are positioned to be offsetoutside by an equal distance x symmetrically with respect to the pivotalcenter Q on an upper part of the rotation base 3, and each are driven torotate by second motors M2, M2′; one ends of first arms 5, 5′ areattached to the first spindles 4, 4′; second spindles 6, 6′ areprotruded on the other ends of the first arms 5, 5′ in a stateindifferent to the rotation of the first arms 5, 5′, which are rotatedeach by a gear rate 2:1 by way of pulleys and timing belts inside thefirst arms 5, 5′, accompanied with the rotation of the first arms 5, 5′;one ends of second arms 7, 7′ are attached to the second spindles 6, 6′;third spindles 8, 8′ are protruded on the other ends of the second arms7, 7′ in a state indifferent to the rotation of the second arms 7, 7′,which are rotated each by a gear rate 1:2 by way of pulleys and timingbelts inside the second arms 7, 7′, accompanied with the rotation of thesecond arms 7, 7′; a distance between the first spindles 4, 4′ and thesecond spindles 6, 6′ is equal to a distance between the second spindles6, 6′ and the third spindles 8, 8′; one ends of third arms 9, 9′ areattached to the third spindles 8, 8′; hands 10, 10′ for holdingsubstrates are firmly attached on the other ends of the third arms 9,9′; centers of the substrates each held by the hands 10, 10′ arepositioned to be offset inside by an equal distance x to the thirdspindles 8, 8′, in a direction opposite to the direction in which thefirst spindles 4, 4′ are positioned to be offset outside by the equaldistance x symmetrically to the pivotal center Q; and when the rotationangle of the rotation base 3 is represented by θ and the rotation anglesof the first arms are each represented by φ, φ′, a control device isprovided which controls the rotation angles θ and φ, φ′, in such amanner that center points of the substrates held by the hands 10, 10′,deviating from the pivotal center Q, move linearly to the body of therobot on the straight lines H, H′ in arbitrary directions withinaccessible ranges of the hands 10, 10′, and the substrates are handedover and taken out to and from a container or containers, while thesubstrates are being rotated.

[0017] The substrate conveyer robot with the above construction is theso-called double arm sequence type substrate conveyer robot having twosequences (a pair) of arm expansion/contraction mechanisms, whichcontain first through third arms 5, 5′, 7, 7′, and 9, 9′ respectively,in a bilateral symmetry. The control device controls the rotation angleθ of the rotation base 3 provided in the body of the robot and therotation angles φ, φ′ of the first arms 5, 5′, so that the center pointsof the substrates held by the hands 10, 10′, deviating from the pivotalcenter Q, move linearly to the body of the robot on the straight linesH, H′ in arbitrary directions within the accessible ranges of the hands10, 10′, and the substrates are handed over and taken out to and fromthe container(s), while the substrates are being rotated. Therefore,when compared with the conventional double arm sequence type substrateconveyer robot, the invention can provide a substrate conveyer robotthat can hand over and take out the substrates to and from thecontainers disposed in arbitrary positions and directions within theaccessible ranges of the hands 10, 10′ of the robot, without increasingthe number of the control axes, at a low production cost.

[0018] Further, in the foregoing construction, the control devicepreferably controls the rotation angles θ and φ, φ′ each so as tosatisfy:

{m+2L sin(φ)}sin(θ)=h(constant),

[0019] or

{m+2L sin(φ′)}sin(θ)=h′(constant),

[0020] where it is assumed that the center points of the substratesdeviate from the pivotal center Q by constant distances h, h′, and movelinearly to the body of the robot on the straight lines H, H′ inarbitrary directions within the accessible ranges of the hands 10, 10′,and that the distance between the first spindles 4, 4′ and the secondspindles 6, 6′, and the distance between the second spindles 6, 6′ andthe third spindles 8, 8′ are represented by L, and a distance before theoffset between the third spindles 8, 8′ and the centers of thesubstrates is represented by m. As the result, the combination controlof these rotation angles θ and φ, φ′ becomes very simple, in which thecenter points of the substrates held by the hands 10, 10′, deviatingfrom the pivotal center Q, move linearly to the body of the robot on thestraight lines H, H′ in arbitrary directions within the accessibleranges of the hands 10, 10′, and the substrates are handed over andtaken out to and from the containers, while the substrates are beingrotated.

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Preferred embodiments of the present invention will be describedin detail based on the following drawings, wherein:

[0022]FIG. 1 is a schematic vertical sectional view of a substrateconveyer robot relating to the first embodiment of the invention;

[0023]FIG. 2 illustrates the state in which the substrate conveyer robotrelating to the first embodiment is used in various operational modes;

[0024]FIG. 3 explains the operational mechanism of the substrateconveyer robot relating to the first embodiment;

[0025]FIG. 4 illustrates the various operational states of the substrateconveyer robot relating to the first embodiment in an overlapped manner;

[0026]FIG. 5 illustrates the various operational states of the substrateconveyer robot relating to the first embodiment separately by eachstate;

[0027]FIG. 6 is a schematic vertical sectional view of a substrateconveyer robot relating to the second embodiment of the invention;

[0028]FIG. 7 illustrates a skeleton in the initial state of thesubstrate conveyer robot relating to the second embodiment;

[0029]FIG. 8 illustrates a skeleton for explaining the operationalmechanism of the substrate conveyer robot relating to the secondembodiment;

[0030]FIG. 9 is a perspective view of the substrate conveyer robotrelating to the first embodiment shown in FIG. 1;

[0031]FIG. 10 is a perspective view of the substrate conveyer robotrelating to the second embodiment shown in FIG. 6; and,

[0032]FIG. 11 illustrates an example of the conventional substrateconveyer robot.

DETAILED DESCRIPTION OF THE INVENTION

[0033] Next, the first embodiment of the invention disclosed in thefirst and the second claims of the application, illustrated in FIG. 1through FIG. 5, and FIG. 9, will be explained.

[0034] The substrate conveyer robot relating to the first embodiment isthe so-called single arm sequence type substrate conveyer robot thatpossesses one sequence of an arm expansion/contraction mechanismcontaining three arms of the first through the third arms, which isused, for example, for conveying a semiconductor wafer substrate.Mostly, such a substrate forms in a disk, and has an orientation flat (apart cut off in a straight line on the edge of the disk) that is usedfor positioning, etc., formed on one part of the circumference.

[0035] As illustrated in FIG. 1, a substrate conveyer robot 1 of thefirst embodiment is furnished inside a robot body 2 with a rotation base3 having a pivotal center Q, which is driven and rotated by the firstmotor M1 via a reduction gear G1. The rotation base 3 is rotated aroundthe pivotal center Q. The first motor M1 is housed and fixed inside anelevation base 55 installed beneath the rotation base 3.

[0036] Inside the body of the rotation base 3, a second motor M2 isfixed on the upper part thereof. A first spindle 4 disposed on the sameaxis as the pivotal center Q, which is driven and rotated by this secondmotor M2 via a reduction gear G2, protrudes from the upper part of thebody of the rotation base 3, in a state independent of the rotation ofthe rotation base 3. Therefore, the first spindle 4 will revolve by therotation of the rotation base 3, but the rotation caused by the secondmotor M2 will not be influenced by the rotation of the rotation base 3.

[0037] The first spindle 4 is firmly attached on one end of the firstarm 5. And, a second spindle 6 protrudes independently of the rotationof the first arm 5 on the other end of the first arm 5, and the secondspindle 6 is rotated by the gear rate of 2:1 via pulleys 11, 12 and atiming belt 13 inside the body of the first arm 5, accompanied with therotation of the first arm 5.

[0038] The pulley 11 is made up with the upper part of the rotation base3 whose diameter is reduced, and this reduced diameter part is intrudedinside the first arm 5 so as not to escape therefrom. The reduction gearG2 is received with a spacing from the reduced diameter part. The pulley12 is made up with the lower part of the second spindle 6 whose diameteris enlarged, and this larger diameter part is received inside the firstarm 5 so as not to escape therefrom. The second spindle 6 is formed intoa hollow cylinder with a stage. The timing belt 13 is put on between thepulleys 11 and 12, and the gear rate of these pulleys 11 and 12 is 2:1.

[0039] Therefore, if the first arm 5 is rotated by the angle of φ withthe first spindle 4, by the rotation of the first spindle 4 that isdriven to rotate by the second motor M2, the rotation of the angle φwill relatively travel the timing belt 13 on the pulley 12 the samelength as the length that the timing belt 13 relatively travels on thepulley 11, so that the amount of rotation of the second spindle 6 causedby this travel of the timing belt 13 will be 2φ, which is twice therotation angle φ of the first arm 5 (the first spindle 4), and therotational direction thereof will be opposite to the rotationaldirection of the first arm 5.

[0040] A smaller diameter part of the second spindle 6, which protrudesfrom the other end of the first arm 5, is firmly attached on one end ofthe second arm 7. And on the other end of the second arm 7, a thirdspindle 8 is provided to project out in a state indifferent to therotational movement of the second arm 7, wherein the third spindle 8 isrotated at the gear rate of 1:2 by way of pulleys 21, 22 and a timingbelt 23, inside the second arm 7, accompanied with the rotationalmovement of the second arm 7. The distance between the second spindle 6and the third spindle 8 is made identical to the distance between thefirst spindle 4 and the second spindle 6.

[0041] The pulley 21 is made up with a cylindrical part integrallyformed with the other end of the first arm 5 that protrudes upward, andthis cylindrical part is intruded inside the second arm 7 so as not toescape therefrom. The smaller diameter part of the second spindle 6 isinserted with a spacing to the cylindrical part, and it protrudes outfrom the other end of the first arm 5 independently of the rotationalmovement of the first arm 5. The pulley 22 is made up with the lowerpart of the third spindle 8 whose diameter is enlarged. The thirdspindle 8 is formed into a hollow cylinder with a stage, and the largerdiameter part (lower part) of the third spindle 8 is received inside thesecond arm 7 so as not to escape therefrom. The timing belt 23 is put onbetween the pulleys 21 and 22, and the gear rate of these pulleys 21 and22 is 1:2.

[0042] Therefore, if the second arm 7 is rotated by the angle of 2φ withthe second spindle 6 by the rotation of the second spindle 6, therotation of the angle 2φ will relatively travel the timing belt 23 onthe pulley 22 the same length as the length that the timing belt 23relatively travels on the pulley 21, so that the amount of rotation ofthe third spindle 8 caused by this travel of the timing belt 23 will beφ, that is, half the rotation angle 2φ of the second arm 7 (the secondspindle 6), and the rotational direction thereof will be opposite to therotational direction of the second arm 7. This indicates that the thirdspindle 8 does not change the attitude of its own, even with therotation of the first arm 5. Moreover, since the distance between thesecond spindle 6 and the third spindle 8 is the same as the distancebetween the first spindle 4 and the second spindle 6, the pivot P3 ofthe third spindle 8 will always be on the straight line J that passesthrough the pivot P1 of the first spindle 4 (and this pivot P1 coincideswith the pivotal center Q). In FIG. 3, for example, when the pivot P2 ofthe second spindle 6 is transferred to P2 ₁ with the rotation, the pivotP3 of the third spindle 8 is transferred to P3 ₁ with the rotation, butthe point P3 ₁ will still be on the straight line J. This straight lineJ is perpendicular (η=90° ) to the straight line that connects the pivotP1 of the first spindle 4 and the initial position P2 ₀ of the pivot P2of the second spindle 6 (refer to FIG. 1, FIG. 3, and FIG. 4(a)). Also,this initial position P2 ₀ is a point to transfer the position inaccordance with the rotation angle θ of the rotation base 3 on the x yabsolute coordinate, which will be described later.

[0043] One end of the third arm 9 is firmly attached on the thirdspindle 8. And, the hand 10 for holding the substrate 30 is fixed on theother end of the third arm 9. As described above, since the thirdspindle 8 does not change the attitude even with the rotation of thefirst arm 5, the third arm 9 and the hand 10 will not change theirattitudes with the rotation of the first arm 5.

[0044] In the first embodiment, the pivot (center point) P4 of thesubstrate 30 held by the hand 10 as well as the pivot P3 of the thirdspindle 8 is always on the straight line J that passes through the pivotP1 of the first spindle 4 (the pivotal center Q). This constant straightline J forms in a fixed straight line on the relative x′ y′ coordinatesystem that is assumed to be on the rotation base 3. The distance R fromthe pivot P4 of the substrate 30 being always on the straight line J tothe pivotal center Q indicates the amount of extension of the armexpansion/contraction mechanism, and is regarded as an important measurefor the operational amount of handing over and taking out the wafersubstrate 30 to and from the cassette 32 (refer to FIG. 4). Since theamount of extension is determined by the rotational amount of the firstarm 5, it can be controlled by controlling the rotational amount of thesecond motor M2 that drives to rotate the first spindle 4. The straightline J corresponds to the robot advancing/retreating axis R in thesubstrate conveyer robot 1 possessing the two control axes, namely therobot revolving axis θ and the robot advancing/retreating axis R.

[0045]FIG. 3 explains each operation of the rotation base 3 and the armexpansion/contraction mechanism containing three arms from the first tothe third 5, 7, and 9, on the x y absolute coordinate that isestablished on the installation surface of the substrate conveyer robot1, and also explains the mechanism of the ultimate movement of the pivotP4 of the substrate 30 along the straight line H on this coordinatesystem as the result of the operation. FIG. 4 illustrates the variousoperational states of the substrate conveyer robot 1 to operate based onthis mechanism, in an overlapped manner with the elapse of time. Also,FIG. 5 illustrates the same various operational states separately withthe elapse of time.

[0046] As illustrated in FIG. 3, the straight line H does not passthrough the pivot P1 (the pivotal center Q) of the first spindle 4, anddeviates from this pivot P1 by a constant distance h. The straight lineJ, as mentioned above, is a fixed straight line on the relative x′ y′coordinate system. Therefore, on the absolute x y coordinate system, thedirection of the straight line J is dependent only on the rotation angleθ of the rotation base 3. The pivotal center Q that forms a rotationalcenter of the rotation base 3 corresponds to the robot revolving axis θin the substrate conveyer robot 1 that possesses the two control axes,the robot revolving axis θ and the robot advancing/ retreating axis R,and forms the control axis when controlling the rotation angle θ of therotation base 3.

[0047] Now, on the absolute x y coordinate system, assuming that therotation angle of the rotation base 3 representing the rotation amountof the straight line J (the rotation amount of the robot hand 10) isgiven by θ, the rotation angle of the first arm 5 (the first spindle 4)measured on the basis of the straight line P1 P2 ₀ is given by φ, thedistance between the first spindle 4 and the second spindle 6 (namely,the distance between P1 and P2)=the distance between the second spindle6 and the third spindle 8 (namely, the distance between P2 and P3) isgiven by L, the distance between the third spindle 8 and the center ofthe substrate 30 (namely, the distance between P3 and P4) is given by m,and the distance between the first spindle 4 and the third spindle 8(namely, the distance between P1(Q) and P3) is given by r, and assumingthat the center point P4 of the substrate 30 held by the hand 10,deviating by the constant distance h from the pivotal center Q, makes alinear movement to the robot body 2 on the straight line H in anarbitrary direction within the accessible range of hand 10, the angle∠P1 P2 P3 that the first arm 5 and the second arm 7 form is 2φ; andtherefore, the distance R between the center point P4 of the substrate30 and the pivotal center Q (that is, the distance between P4 and P1) isrepresented by:

R=m+r=m+2L sin(φ).

[0048] When representing the center point P4 of the substrate 30according to the orthogonal coordinate (x, y), $\begin{matrix}{{{P4}\left( {x,y} \right)} = {{P4}\left( {{R\quad {\cos (\theta)}},{R\quad {\sin (\theta)}}} \right)}} \\{= {{{P4}\left\lbrack {{\left\{ {m + {2L\quad {\sin (\varphi)}}} \right\} {\cos (\theta)}},{\left\{ {m + {2L\quad {\sin (\varphi)}}} \right\} {\sin (\theta)}}} \right\rbrack}.}}\end{matrix}$

[0049] Accordingly, in order for the center point P4 of the substrate 30to always travel straight on the straight line H being parallel to theaxis x, the rotation angles θ and φ should be controlled by controllingthe rotation amount of the first motor M1 and that of the second motorM2, so as to satisfy the following:

{m+2L sin(φ)}sin(θ)=h(constant)  (formula 1).

[0050] The control device 40 (refer to FIG. 1) controls each of therotation amount of the first motor M1 and that of the second motor M2,so that the rotation angles θ and φ always satisfy the above formula 1.

[0051] Further in this case, as illustrated in FIG. 4(a) through FIG.4(d), and FIG. 5(a) through FIG. 5(d), the center point P4 of thesubstrate 30 moves on the straight line H, while the whole substrate 30is being rotated around the center point P4. The substrate 30 canconveniently be inserted into the cassette 32 without colliding againstor making contacts with the inner wall of the cassette 32 during theinsertion, since the outline of the substrate 30 is circular except forthe one part (the orientation flat part). The same can be said fortaking out the substrate 30 from the cassette 32.

[0052] The cassette 32 may be positioned in an arbitrary position anddirection, as long as it is within the accessible range of the robothand 10. Moreover, since it includes a case such that the straight lineH used for the insertion of the substrate 30 into the cassette 32 (thetravel locus of the substrate 30 during the insertion) does not passthrough the pivotal center Q, as illustrated in FIG. 2(a) through FIG.2(c), the wafer substrate 30 can be handed over and taken out,corresponding to various positioning forms of the cassette 32. Besides,in regard to the robot 1 with the configuration illustrated in FIG. 1,since the pivotal center Q, around which all the arms of the robot (thewhole arm expansion/contraction mechanism) revolve, and the pivot P1 ofthe first spindle 4 are made to coincide with each other, the firstmotor M1 and the second motor M2 should simply be controlled so that therotation angles θ and φ satisfy the very simple formula 1, thus makingthe control method very simple.

[0053] The substrate conveyer robot 1 relating to the first embodimentfurther possesses an ascent/descent mechanism 50, which lifts and lowersthe rotation base 3 and the whole arm expansion/contraction mechanism.The ascent/descent mechanism 50 includes the third motor M3 being adriving source of the mechanism, pulleys 52, 53, and a timing belt 54.The pulleys 52, 53, and the timing belt 54 transmit the output of thethird motor M3 to a ball screw mechanism 51. By the rotation of thethird motor M3, the ascent/descent mechanism 50 brings up and down anelevation base 55 that contains the first motor M1, thereby lifts andlowers the rotation base 3 that is established on the upper part of theelevation base 55, and the whole arm expansion/contraction mechanismvertically in the Z-axis direction. Therefore, the substrate conveyerrobot 1 possesses the robot ascending/descending axis Z as the thirdcontrol axis, other than the two control axes, the robot revolving axisθ and the robot advancing/retreating axis R. As the result, thesubstrate conveyer robot 1 is able to comply with plural cassettes 32positioned in different height levels.

[0054] Since it is configured as described above, the first embodimentyields the following effects.

[0055] In the single arm sequence type substrate conveyer robot 1possessing one sequence of the arm expansion/contraction mechanism thatcomprises the first through the third arms, 5, 7 and 9, the rotationangle θ of the rotation base 3 that are furnished inside the robot body2 and the rotation angle φ of the first arm 5 are controlled by thecontrol device 40 in such a manner that the center point P4 of thesubstrate 30 held by the hand 10, deviating from the pivotal center Q,moves linearly to the robot body 2 on the straight line H in anarbitrary direction within the accessible range of the robot hand 10,and the substrate 30, while being rotated, can be handed over and takenout to and from the cassette 32. Therefore, compared with theconventional single arm sequence type substrate conveyer robot, thisembodiment provides an inexpensive substrate conveyer robot that canhand over and take out the substrate 30 to and from the cassette 32being disposed in an arbitrary position and direction within theaccessible range of the robot hand 10, without increasing the number ofthe control axes. Moreover, since the control of the rotation angles θand φ by the control device 40 should only be the control such thatthese rotation angles θ and φ always satisfy the foregoing formula 1,the combination control of these rotation angles θ and φ will becomeextremely simple.

[0056] Next, the second embodiment of the invention disclosed in claim 3and claim 4 of the application will be explained with reference to FIG.6 through FIG. 8, and FIG. 10.

[0057] The substrate conveyer robot relating to the second embodiment,as illustrated in FIG. 6 and FIG. 10, is configured as the so-calleddouble arm sequence type substrate conveyer robot 1′ that includes onepair (two sequences) of the arm expansion/contraction mechanisms in abilateral symmetry, which are composed of three arms, the first armthrough the third arm respectively.

[0058] In the arm expansion/contraction mechanisms of the arm sequencesA and B configuring the double arm sequence, as illustrated in FIG. 6and FIG. 7, the pivots P1 and P1′ of the first spindles 4 and 4′ areplaced at symmetrical positions to the pivotal center Q of the rotationbase 3 to be offset outside by an equal distance x, and the secondmotors M2 and M2′ as the driving sources are furnished to the firstspindles 4 and 4′, respectively. Also, the center points P4 and P4′ ofthe substrates 30 and 30′ each held by the hands 10 and 10′ arepositioned to be offset inside by the equal distance x to the pivots P3and P3′ of the third spindles 8 and 8′, in a direction opposite to thedirection in which the pivots P1 and P1′ of the first spindles 4 and 4′are placed at the symmetrical positions to the pivotal center Q to beoffset outside by the equal distance x to the pivotal center Q.

[0059] There are several methods of achieving the configuration suchthat one ends of the third arms 9 and 9′ each are attached to the thirdspindle 8 and 8′, and the hands 10 and 10′ for holding the substrates 30and 30′ are fastened on the other ends of the third arms 9 and 9′, andas described above, the center points P4 and P4′ of the substrates 30and 30′ are positioned to be offset inside by the equal distance x tothe pivots P3 and P3′ of the third spindles 8 and 8′. In short, theoffset amount of the centers P4 and P4′ of the substrates 30 and 30′ tothe pivots P3 and P3′ of the third spindles 8 and 8′ only needs to beset inside to x (in the direction opposite to the direction in which thecenters P1 and P1′ of the first spindles 4 and 4′ are placed to beoffset outside to the pivotal center Q). As illustrated in FIG. 7 andFIG. 8, there is a method of disposing the hands 10 and 10′perpendicularly to the third arms 9 and 9′, respectively, andpositioning the hands 10 and 10′ along the straight line J, which is oneof the most comprehensible examples. Here, the straight line J is a lineconnecting each of the centers P4 and P4′ of the substrates 30 and 30′with the pivotal center Q, which corresponds to the robotadvancing/retreating axis R as the control axis.

[0060] The arm expansion/contraction mechanism of each of the armsequences A and B in the double arm sequence type substrate conveyerrobot 1′ of the second embodiment differs from that in the single armsequence type substrate conveyer robot 1 of the first embodiment interms of the points mentioned above. However, the configuration and theoperation do not basically differ from those of the first embodiment.The movements of the center points P4 and P4′ of the substrates 30 and30′ on the straight line J are also the same as those of the firstembodiment. The rotation base 3 is shared by the armexpansion/contraction mechanisms of the arm sequences A and B for therevolution of the whole arm expansion/contraction mechanisms, and therotation angle θ around the pivotal center Q (the robot revolving axisθ) of the rotation base 3 becomes the revolution angle of each of thearm expansion/contraction mechanisms as it is.

[0061] As mentioned above, the movement of the arm expansion/contractionmechanism of each of the arm sequences A and B in the double armsequence type substrate conveyer robot 1′ of the second embodiment isthe same as that of the arm expansion/contraction mechanism in thesingle arm sequence type substrate conveyer robot 1 of the firstembodiment. The arm expansion/contraction mechanisms of the armsequences A and B share the pivotal center Q and use it alternately,thereby each being able to convey the substrates 30 and 30′ toward thecassette 32, while the arm expansion/contraction mechanisms each rotatethe substrates 30 and 30′ independently alternately and move them on thestraight lines H and H′ deviating from the pivotal center Q, whichextend toward the aperture plane of the cassette 32. Naturally, thisrobot is able to perform a conveyance movement such that the centerpoints P4 and P4′ of the substrates 30 and 30′ move on the straight lineJ passing through the pivotal center Q, in the same manner as theconventional substrate conveyer robot.

[0062] In regard to the arm expansion/contraction mechanisms of the armsequences A and B in the double arm sequence type substrate conveyerrobot 1′, the setting of the offset from the pivotal center Q of thepivots P1 and P1′ of the first spindles 4 and 4′ to the amount describedabove, satisfies the following formulas, in the same manner as thesingle arm sequence type substrate conveyer robot 1:

{m+2L sin(φ)}sin(θ)=h(constant)  (formula 1)

[0063] or,

{m+2L sin(φ′)}sin(θ)=h′(constant)  (formula 1′),

[0064] where it is assumed that the distance before the offset betweenthe third spindles 8 and 8′ and the centers of the substrates 30 and 30′is represented by m.

[0065] The control device 40′ only needs to control the first motor M1and the second motor M2, and the first motor M1′ and the second motorM2′, by turns, so that the rotation angle θ of the rotation base 3 andthe rotation angles φ and φ′ of the first arms 5, 5′ always satisfy theabove formula 1 and formula 1′. Thus, the arm expansion/contractionmechanism of the arm sequence A can take out the unprocessed substrate30 from the cassette 32 that is positioned in an arbitrary position anddirection within the accessible range of the hands 10 and 10′, and thearm expansion/contraction mechanism of the arm sequence B can return theprocessed substrate 30′ to the cassette 32 by turns. Off course, twocassettes can be used, one of which is used for containing unprocessedsubstrates 30, and another of which is used for containing processedsubstrates 30.

[0066] Each of the members constituting the arm expansion/contractionmechanism of the arm sequence B and the other members is given the mark(′) on the symbol attached to each of the corresponding membersconstituting the arm expansion/contraction mechanism of the arm sequenceA and the other corresponding members, thereby further detailedexplanations of the double arm sequence type substrate conveyer robot 1′of the second embodiment will be omitted.

[0067] Being configured as mentioned above, the second embodiment yieldsthe following effects.

[0068] In the double arm sequence type substrate conveyer robot 1′possessing symmetrically two sequences (a pair) of the arm expansion/contraction mechanisms composed of the first through the third arms 5,5′, 7, 7′, and 9, 9′, the rotation angle θ of the rotation base 3 thatare furnished inside the robot body 2 and the rotation angles φand φ′ ofthe first arms 5, 5′ are controlled by the control device 40′ in such amanner that the center points P4 and P4′ of the substrates 30 and 30′held by the hands 10 and 10′, deviating from the pivotal center Q by theconstant distances h and h′, move linearly each to the robot body 2 onthe straight lines H and H′ in arbitrary directions within theaccessible ranges of the hands 10 and 10′, and the substrates 30 and30′, while being rotated, can be handed over and taken out to and fromthe cassette(s) 32. Therefore, compared with the conventional double armsequence type substrate conveyer robot, the second embodiment providesan inexpensive substrate conveyer robot 1′ that can hand over and takeout the substrates 30 and 30′ to and from the cassette(s) 32 beingdisposed in arbitrary positions and directions within the accessibleranges of the robot hand 10 and 10′ without increasing the number of thecontrol axes.

[0069] Besides, since the control of the rotation angles θ and φ, φ′ bythe control device 40′ should only be the control such that theserotation angles θ and φ, φ′ always satisfy the foregoing formula 1 andformula 1′, the arm expansion/contraction mechanism of each of the armsequences A and B is able to employ a common control method, thus makingthe combination control of these rotation angles θ and φ, φ′ extremelysimple.

What is claimed is:
 1. A substrate conveyer robot provided with arotation base driven to rotate by a first motor inside a body of arobot, possessing a pivotal center, the substrate conveyer robotwherein: a first spindle is protruded in a state indifferent to therotation of the rotation base, which is positioned coaxially with thepivotal center on an upper part of the rotation base, and is driven torotate by a second motor; one end of a first arm is attached to thefirst spindle; a second spindle is protruded on the other end of thefirst arm in a state indifferent to the rotation of the first arm, whichis rotated by a gear rate 2:1 by way of pulleys and a timing belt insidethe first arm, accompanied with the rotation of the first arm; one endof a second arm is attached to the second spindle; a third spindle isprotruded on the other end of the second arm in a state indifferent tothe rotation of the second arm, which is rotated by a gear rate 1:2 byway of pulleys and a timing belt inside the second arm, accompanied withthe rotation of the second arm; a distance between the first spindle andthe second spindle is equal to a distance between the second spindle andthe third spindle; one end of a third arm is attached to the thirdspindle; a hand for holding a substrate is firmly attached on the otherend of the third arm; and, when the rotation angle of the rotation baseis represented by θ and the rotation angle of the first arm isrepresented by φ, a control device is provided which controls therotation angles θ and φ in such a manner that a center point of thesubstrate held by the hand, deviating from the pivotal center, moveslinearly to the body of the robot on the straight line in an arbitrarydirection within an accessible range of the hand, and the substrate ishanded over and taken out to and from a container, while being rotated.2. A substrate conveyer robot as claimed in claim 1, wherein, when it isassumed that the center point of the substrate deviates from the pivotalcenter by a constant distance h, and moves linearly to the body of therobot on the straight line in an arbitrary direction within theaccessible range of the hand, and that the distance between the firstspindle and the second spindle and the distance between the secondspindle and the third spindle are represented by L, and a distancebetween the third spindle and the center of the substrate is representedby m, the rotation angles θ and φ each are controlled so as to satisfythe following: {m+2L sin(φ)}sin(θ)=h(constant).
 3. A substrate conveyerrobot provided with a rotation base driven to rotate by a first motorinside a body of a robot, possessing a pivotal center, the substrateconveyer robot wherein: first spindles are protruded in a stateindifferent to a rotation of the rotation base, which are positioned tobe offset outside by an equal distance x symmetrically with respect tothe pivotal center on an upper part of the rotation base, and each aredriven to rotate by second motors; one ends of first arms are attachedto the first spindles; second spindles are protruded on the other endsof the first arms in a state indifferent to the rotation of the firstarms, which are rotated each by a gear rate 2:1 by way of pulleys andtiming belts inside the first arms, accompanied with the rotation of thefirst arms; one ends of second arms are attached to the second spindles;third spindles are protruded on the other ends of the second arms in astate indifferent to the rotation of the second arms, which are rotatedeach by a gear rate 1:2 by way of pulleys and timing belts inside thesecond arms, accompanied with the rotation of the second arms; adistance between the first spindles and the second spindles is equal toa distance between the second spindles and the third spindles; one endsof third arms are attached to the third spindles; hands for holdingsubstrates are firmly attached on the other ends of the third arms;centers of the substrates each held by the hands are positioned to beoffset inside by an equal distance x to the third spindles, in adirection opposite to the direction in which the first spindles arepositioned to be offset outside by the equal distance x symmetrically tothe pivotal center; and when the rotation angle of the rotation base isrepresented by θ and the rotation angles of the first arms are eachrepresented by φ, φ′, a control device is provided which controls therotation angles θ and φ, φ′, in such a manner that center points of thesubstrates held by the hands, deviating from the pivotal center, movelinearly to the body of the robot on the straight lines in arbitrarydirections within accessible ranges of the hands, and the substrates arehanded over and taken out to and from a container or containers, whilebeing rotated.
 4. A substrate conveyer robot as claimed in claim 3,wherein, when it is assumed that the center points of the substratesdeviate from the pivotal center by constant distances h, h′, and movelinearly to the body of the robot on the straight lines in arbitrarydirections within the accessible ranges of the hands, and that thedistance between the first spindles and the second spindles and thedistance between the second spindles and the third spindles arerepresented by L, and a distance before the offset between the thirdspindles and the center points of the substrates is represented by m,the rotation angles θ and φ, φ′ each are controlled so as to satisfy thefollowing: {m+2L sin(φ)}sin(θ)=h(constant), or, {m+2Lsin(φ′)}sin(θ)=h′(constant).